This here just sounds like you're assuming that Minato preformed one-handed seals as his main style. Last time he was alive, he had two hands, so he really never had need to use a one handed seal if he had two hands.But still, two shinobi in the entire world who know how to do one-handed seals, and one happens to be Kakashi's sensei and he still doesn't know about it? You would think Minato would be known specifically for that feat.
I doubt there are some jutsu that simply only use a single hand. In part 1 he reacted as if it was conceptually impossible. And this is the man who has copied over 1000 jutsu. I just find it strange.
Just my thoughts.